The present invention relates to apparatus for inserting the electric heating element wire into the fabric shell of an electric blanket. An electric blanket conventionally consists of two layers of fabric between which is sandwiched a heating element arranged in a tortuous fashion so as to cover essentially the entire area of the blanket. When the heating element is energized it delivers heat in a uniform manner to the entire surface of the blanket even though the heating element which is looped back and forth across the blanket is spaced from the adjacent legs by a number of inches. There are various types of electric blankets which utilize heating elements and temperature sensing means which differ in structure and functions from each other.
All electric blankets have some type of elongated heating element which heats by virtue of the electricity passing through one or more conductors. In addition, it is necessary that such blankets include some type of sensing means to determine when the blanket wire has become overheated and is likely to cause injury to the user or to start a fire. These temperature sensors or safety means may comprise a plurality of thermostats spaced throughout the length of the heating element or may comprise a continuous wire sensor to be associated with heating element wire or in closely spaced relationship with the heating element wire throughout the blanket. In any event, the necessity for the temperature sensing or temperature control means throughout the blanket has resulted in a structure which is somewhat difficult to insert between the spaced layers of the blanket fabric. The present invention has been applied to blanket heating wire which has its temperature sensing means integral with the wire and which has no spaced bimetallic thermostats to interfere with inserting the wire into the blanket.
Generally the layers of the blanket material are secured together along strips extending across or lengthwise of the blanket to provide a series of adjacent parallel channels or passageways through which the heating element wire may extend. There have been some attempts in the past to place the element wire between the layers of fabric before securing the fabric together but this approach has not proven very satisfactory. Alternatively, there have been many different approaches to manually inserting the wire back and forth through the adjacent channels of the blanket shell to complete the insertion of the element wire. In most cases these processes have been expensive, time consuming and very labor intensive. Accordingly, there is a recognized need for an automatic machine for inserting the blanket heating wire into the blanket shell with a minimum amount of labor.